1. Field of the Invention
The present invention is generally related to an engine with a crankshaft and, more particularly, to a crankshaft that provides surfaces which induce a flow of air and oil mist in a preferred direction when the crankshaft is rotated about its rotational axis.
2. Description of the Prior Art
Those skilled in the art of internal combustion engines are aware of many different types of crankshafts. The purpose of the crankshaft is to convert the reciprocal movement of pistons within the internal combustion engine to rotational movement of an output shaft. Counterweights are often used to balance the rotational forces that result from the rotation of the crankshaft about its rotational axis.
U.S. Pat. No. 4,015,908, which issued to Ashley on Apr. 5, 1977, describes a multiple piece crankshaft which is produced by chamfering one end of each crank arm opening and providing keyways in and parallel to the chamfered surfaces. Each crankshaft and crankpin is provided with a shoulder and is positioned in a crank arm opening with the shoulder opposite the chamfer. The projecting ends of the shaft and pin are cold formed into the respective chamfer and keyways.
U.S. Pat. No. 4,342,236, which issued to Everts on Aug. 3, 1982, describes a crankshaft with laminated counterweights. The counterweight comprises a plurality of substantially flat plates, each of which has a first and a second shaft mounting hole therethrough and at least one depression on one side and a boss on the other side.
U.S. Pat. No. 4,534,241, which issued to Remmerfelt et al. on Aug. 13, 1985, describes a crankshaft for combustion engines. The crankshaft comprises a number of components joined to each other. Each component comprises a counterweight, a portion of a main bearing journal, and a portion of a crank bearing journal.
U.S. Pat. No. 4,697,556, which issued to Mondek et al. on Oct. 6, 1987, describes a marine propulsion device crankshaft bearing arrangement. The marine propulsion device comprises a lower unit including a rotatably mounted propeller and an internal combustion engine drivingly connected to the propeller. Within an engine block of the outboard motor, a crankshaft is rotatably supported by the engine block and includes an end portion projecting from the engine block. A flywheel includes a hub that is mounted on the end portion of the crankshaft.
U.S. Pat. No. 4,768,397, which issued to Adams on Sep. 6, 1988, describes a lubrication scheme for pressure lubricated crankshafts with counterweight holes for crankshaft balance. A method and apparatus for counterbalancing an internal combustion engine while maintaining a lubricant flow path for supplying lubricant to a crankshaft connecting rod journal is described. A generally cylindrical mass of crankshaft material is removed from a region of the crankshaft located coaxial with the connecting rod journal for engine balancing purposes with that removed mass including a portion of the lubricant passageway.
U.S. Pat. No. 5,031,591, which issued to Shinoda et al. on Jul. 16, 1991, describes an overhead cam vertical crankshaft engine. The engine comprises a vertically disposed crankshaft having a first timing pulley at its lower end. The need for lubrication for the transmission mechanism between the crankshaft and the cam shaft is substantially eliminated and the noise generation is reduced.
U.S. Pat. No. 5,899,120, which issued to Leith on May 4, 1999, describes a crankshaft with a laminated counterweight. The counterweight is used for connecting the main shaft with the crankpin of a crankshaft in which the counterweight includes a pair of end laminations which are circular in shape and have a central opening dimension to receive the main shaft and a crank pin opening radially spaced from the central opening and dimensioned to receive the crankpin.
U.S. Pat. No. 6,164,259, which issued to Brogdon et al. on Dec. 26, 2000, describes an engine balance apparatus and accessory drive device. The balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons is described. The balancing mechanism may comprise a first balance mass non-rotatably affixed to the crankshaft and a second balance mass rotatably supported on the crankshaft.
U.S. Pat. No. 6,418,902, which issued to Ericson on Jul. 16, 2002, describes a composite full circle crankshaft counterweight. Composite crankshaft counterweights are described for a two-cycle internal combustion engine. They include a “T”-shaped counterweight surrounded by a cup-shaped retainer that holds lightweight inserts against the counterweight.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Many different types of counterweights are well known to those skilled in the art. Counterweights are typically used for the sole purpose of balancing the crankshaft to avoid vibration when the crankshaft rotates about its rotational axis. It would be significantly beneficial if the crankshaft could be shaped in such a way that it also performs the helpful function of assisting the flow of air and oil mist in a preferred direction in the vicinity of the crankshaft.